Providing 3D look-up table (LUT) estimation for color gamut scalability

ABSTRACT

Systems and/or methods for estimating color conversion components. A video coding device may receive a picture associated with a first color space. The picture may comprise a first component at a first sampling location, a second component at a second sampling location and the second component at a third sampling location. The video coding device may apply a first interpolation filter to the second component at the second sampling location and the second component at the third sampling location to determine the second component at the first sampling location. The second component at the first sampling location may be associated with the first color space. The video coding device may apply a color conversion model to the first component at the first sampling location and to the second component at the first sampling location to translate the first component at the first sampling location to a second color space.

CROSS REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/915,892 filed on Dec. 13, 2013, the contents of which are each herebyincorporated by reference herein in their entirety.

BACKGROUND

The phase of luma and chroma sample locations of an input video streammay not be aligned. Such a misalignment of the luma and chroma samplelocations may affect the precision of 3D LUT interpolation and, thus,the 3D LUT that may be estimated.

SUMMARY

Systems and/or methods for estimating color conversion components. Avideo coding device may receive a picture associated with a first colorspace. The picture may comprise a first component at a first samplinglocation, a second component at a second sampling location and thesecond component at a third sampling location. The video coding devicemay apply a first interpolation filter to the second component at thesecond sampling location and the second component at the third samplinglocation to determine the second component at the first samplinglocation. The second component at the first sampling location may beassociated with the first color space. The video coding device may applya color conversion model to the first component at the first samplinglocation and to the second component at the first sampling location totranslate the first component at the first sampling location to a secondcolor space. The first component may be a luma component and the secondcomponent may be a first chroma component (e.g., red difference chromacomponent and/or blue difference chroma component) or a second chromacomponent (e.g., red difference chroma component and/or blue differencechroma component). The first component may be the first chroma component(e.g., red difference chroma component and/or blue difference chromacomponent) or the second chroma component and the second component maybe the luma component.

The video coding device may apply the first interpolation filter. Thefirst interpolation filter may include: multiplying the second componentat the second sampling location by three; adding the multiplied secondcomponent at the second sampling location, the second component at thethird sampling location, and two to determine a sum; and dividing thesum by four. The first interpolation filter may include: adding thesecond component at the second sampling location, the second componentat the third sampling location, and one to determine a sum; and dividingthe sum by two.

The picture may comprises the second component at a fourth samplinglocation and the second component at a fifth sampling location. Thevideo coding device may apply the first interpolation filter to thesecond component at the second sampling location, the second componentat the third sampling location, the second component at the fourthsampling location, and the second component at the fifth samplinglocation to determine the second component at the first samplinglocation. The first interpolation filter may include: adding the secondcomponent at the second sampling location and the second component atthe third sampling location to determine a first sum; adding the secondcomponent at the fourth sampling location and the second component atthe fifth sampling location to determine a second sum; multiplying thesecond sum by three to determine a third sum; adding the first sum, thethird sum, and four to determine a fourth sum; and dividing the fourthsum by eight.

The picture may comprises a third component at the second samplinglocation and a third component at the third sampling location. The firstcomponent may be a luma component, the second component may be a reddifference chroma component, and the third component may be a bluedifference chroma component. The video coding device may apply the firstinterpolation filter to the third component at the second samplinglocation and the third component at the third sampling location todetermine the third component at the first sampling location. The thirdcomponent at the first sampling location may be associated with thefirst color space. The video coding device may apply the colorconversion model to the first component at the first sampling location,to the second component at the first sampling location, and to the thirdcomponent at the first sampling location to translate the firstcomponent at the first sampling location to the second color space.

The picture may comprise a third component at the first samplinglocation. This video coding device may apply the color conversion modelto the first component at the first sampling location, to the thirdcomponent at the first sampling location and to the second component atthe first sampling location to translate the first component at thefirst sampling location to the second color space. The first componentmay be a first chroma component, the second component may be a lumacomponent, and the third component may be a second chroma component. Thefirst component may be the second chroma component, the second componentmay be a luma component, and the third component may be the first chromacomponent.

The picture may be characterized by a 4:2:0 chroma format. The colorconversion model may be based on a 3-dimensional look up table (LUT).

The video coding device of claim 1, wherein the processor is furtherconfigured to receive a scalable bitstream, the scalable bitstreamcomprising a base layer and an enhancement layer, wherein the base layercomprises the picture, the base layer is associated with the first colorspace and the enhancement layer is associated with the second colorspace.

A video coding device may receive a picture associated with a firstcolor space. The picture may comprise a first chroma component at afirst sampling location, a second chroma component at the first samplinglocation, a luma component at a second sampling location, a lumacomponent at a third sampling location, a luma component at a fourthsampling location, and a luma component at a fifth sampling location.The video coding device may apply a first interpolation filter to two ormore of the luma component at the second sampling location, the lumacomponent at the third sampling location, the luma component at thefourth sampling location, and the luma component at the fifth samplinglocation to determine the luma component at the first sampling location,wherein the luma component at the first sampling location is associatedwith the first color space. The video coding device may apply a colorconversion model to the first chroma component at the first samplinglocation, the second chroma component at the first sampling location,and to the luma component at the first sampling location to translatethe first chroma component at the first sampling location to a secondcolor space. The video coding device may apply the color conversionmodel to the first chroma component at the first sampling location, thesecond chroma component at the first sampling location, and to the lumacomponent at the first sampling location to translate the second chromacomponent at the first sampling location to the second color space. Thefirst chroma component and/or the second chroma component may be a reddifference chroma component and/or a blue difference chroma component.

A video coding device may receive a picture associated with a firstcolor space. The picture may comprise a luma component at a firstsampling location, a first chroma component at a second samplinglocation, a second chroma component at the second sampling location, thefirst chroma component at a third sampling location, the second chromacomponent at the third sampling location, the first chroma component ata fourth sampling location, the second chroma component at the fourthsampling location, the first chroma component at a fifth samplinglocation, and the second chroma component at the fifth samplinglocation. The video coding device may apply a first interpolation filterto two or more of the first chroma component at the second samplinglocation, the first chroma component at the third sampling location, thefirst chroma component at the fourth sampling location, and the firstchroma component at the fifth sampling location to determine the firstchroma component at the first sampling location, wherein the firstchroma component at the first sampling location is associated with thefirst color space. The video coding device may apply the firstinterpolation filter to two or more of the second chroma component atthe second sampling location, the second chroma component at the thirdsampling location, the second chroma component at the fourth samplinglocation, and the second chroma component at the fifth sampling locationto determine the second chroma component at the first sampling location,wherein the second chroma component at the first sampling location isassociated with the first color space. The video coding device may applya color conversion model to the luma component at the first samplinglocation, the first chroma component at the first sampling location, andthe second chroma component at the first sampling location to translatethe luma component at the first sampling location to a second colorspace. The first chroma component and/or the second chroma component maybe a red difference chroma component and/or a blue difference chromacomponent.

A video coding device may be configured to receive a picture associatedwith a first color space. The picture may comprise a first component ata first sampling location, the first component at a second samplinglocation, a second component at a third sampling location, the secondcomponent at a fourth sampling location, the second component at a fifthsampling location, and the second component at a sixth samplinglocation. The video coding device may be configured to apply a firstinterpolation filter to the second component at the third samplinglocation and the second component at the fourth sampling location todetermine the second component at the first sampling location. Thesecond component at the first sampling location may be associated withthe first color space. The video coding device may be configured toapply a second interpolation filter to the second component at the thirdsampling location, the second component at the fourth sampling location,the second component at the fifth sampling location and the secondcomponent at the sixth sampling location to determine the secondcomponent at the second sampling location. The second component at thesecond sampling location may be associated with the first color space.The video coding device may be configured to apply a color conversionmodel to the first component at the first sampling location and to thesecond component at the first sampling location to translate the firstcomponent at the first sampling location to a second color space. Thevideo coding device may be configured to apply the color conversionmodel to the first component at the second sampling location and to thesecond component at the second sampling location to translate the firstcomponent at the second sampling location to the second color space.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file includes at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a block diagram of an example of a scalable video codingsystem with one or more layers such as N layers.

FIG. 2 is an example of temporal and/or inter-layer prediction forstereoscopic (e.g., 2-view) video coding using MVC.

FIG. 3 is an example color primary comparison between a BT.709 (HDTV)and a BT.2020 (UHDTV) in a CIE color definition or space.

FIG. 4A is an example of a visual difference to an end user between apicture graded in BT.709 and rendered in BT.709.

FIG. 4B is an example of a visual difference to an end user between apicture graded in BT.2020 and rendered in BT.709.

FIG. 5 is an example of color gamut scalability (CGS) coding withpicture level inter-layer prediction (ILP).

FIG. 6 is an example of a 3D look-up table for an 8-bit YUV signal.

FIG. 7 is an example of a weight calculation in a tri-linear ortetrahedral interpolation (e.g., that may be used in a 3D LUTestimation).

FIG. 8 is an example of a tetrahedral interpolation (e.g., that may beused in a 3D LUT estimation).

FIGS. 9A-9F are examples of tetrahedrons that may encompass aninterpolating point (e.g., that may be used in 3D LUT estimation).

FIG. 10 is an example of a phase shift between a luma and chromacomponent for a chroma format (e.g., for a 420 chroma format) where asquare may represent a luma pixel grid and a circle may represent achroma grid.

FIG. 11A is a diagram of an example communications system in which oneor more disclosed embodiments may be implemented.

FIG. 11B is a system diagram of an example wireless transmit/receiveunit (WTRU) that may be used within the communications systemillustrated in FIG. 11A.

FIG. 11C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 11A.

FIG. 11D is a system diagram of another example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 11A.

FIG. 11E is a system diagram of another example radio access network andan example core network that may be used within the communicationssystem illustrated in FIG. 11A.

DETAILED DESCRIPTION

Digital video compression technologies may enable efficient digitalvideo communication, distribution and consumption, such as H.261,MPEG-1, MPEG-2, H.263, MPEG-4 part2 and H.264/MPEG-4 part 10 AVC.

Compared to traditional digital video services, such as sending TVsignals over satellite, cable and terrestrial transmission channels,more and more video applications, such as IPTV, video chat, mobilevideo, and streaming video, may be deployed in heterogeneousenvironments. For example, video applications may provide videostreaming in networks with different size cells, and/or the like.Heterogeneity may exist on or at a client, as well as in a network. Forexample, on the client side, an N-screen scenario that is consumingvideo content on devices with varying screen sizes and displaycapabilities, including a smart phone, tablet, PC and TV, and/or thelike may be provided and/or used. On the network side, video may betransmitted across the Internet, WiFi networks, mobile (3G and 4G)networks, and/or any combination thereof.

Scalable video coding may encode a signal once at the highestresolution. Scalable video coding may enable decoding from subsets ofthe streams depending on the specific rate and resolution required bycertain application and/or supported by the client device. Theresolution may be defined by a number of video parameters including, butnot limited to, spatial resolution (e.g., picture size), temporalresolution (e.g., frame rate), video quality (e.g., subjective qualitysuch as MOS, and/or objective quality such as PSNR or SSIM or VQM),and/or the like. Other commonly used video parameters may include achroma format (e.g., such as YUV420 or YUV422 or YUV444), bit-depth(e.g., such as 8-bit or 10-bit video), complexity, view, gamut, and/oraspect ratio (e.g., 16:9 or 4:3). International video standards such asMPEG-2 Video, H.263, MPEG4 Visual and H.264 may have tools and/orprofiles that support scalability modes.

Scalable video coding may enable the transmission and decoding ofpartial bitstreams. The transmission and decoding of partial bitstreamsmay enable a scalable video coding (SVC) system to provide videoservices with lower temporal and/or spatial resolutions or reducedfidelity, while retaining a relatively high reconstruction quality(e.g., given respective rates of the partial bitstreams). SVC may beimplemented with single loop decoding, such that an SVC decoder may setup one motion compensation loop at a layer being decoded, and may notset up motion compensation loops at one or more other lower layers. Forexample, a bitstream may include two layers, including a first layer(e.g., layer 1) that may be a base layer and a second layer (e.g., layer2) that may be an enhancement layer. When such an SVC decoderreconstructs layer 2 video, the setup of a decoded picture buffer andmotion compensated prediction may be limited to layer 2. In such animplementation of SVC, respective reference pictures from lower layersmay not be fully reconstructed, which may reduce computationalcomplexity and/or memory consumption at the decoder.

Single loop decoding may be achieved by constrained inter-layer textureprediction, where, for a current block in a given layer, spatial textureprediction from a lower layer may be permitted if a corresponding lowerlayer block is coded in intra mode. This may be referred to asrestricted intra prediction. When a lower layer block is coded in intramode, it may be reconstructed without motion compensation operationsand/or a decoded picture buffer.

SVC may implement one or more additional inter-layer predictiontechniques such as motion vector prediction, residual prediction, modeprediction, etc., from one or more lower layers. This may improverate-distortion efficiency of an enhancement layer. An SVCimplementation with single loop decoding may exhibit reducedcomputational complexity and/or reduced memory consumption at thedecoder, and may exhibit increased implementation complexity, forexample, due to reliance on block-level inter-layer prediction. Tocompensate for a performance penalty that may be incurred by imposing asingle loop decoding constraint, encoder design and computationcomplexity may be increased to achieve desired performance. Coding ofinterlaced content may not be supported by SVC.

FIG. 1 is a simplified block diagram depicting an example block-based,hybrid scalable video coding (SVC) system. A spatial and/or temporalsignal resolution to be represented by the layer 1 (e.g., base layer)may be generated by downsampling of the input video signal. In asubsequent encoding stage, a setting of the quantizer such as Q1 maylead to a quality level of the base information. One or more subsequenthigher layer(s) may be encoded and/or decoded using the base-layerreconstruction Y1, which may represent an approximation of higher layerresolution levels. An upsampling unit may perform upsampling of the baselayer reconstruction signal to a resolution of layer-2. Downsamplingand/or upsampling may be performed throughout a plurality of layers(e.g., for N layers, layers 1, 2 . . . N). Downsampling and/orupsampling ratios may be different, for example depending on a dimensionof a scalability between two layers.

In the example scalable video coding system of FIG. 1, for a givenhigher layer n (e.g., 2≦n≦N, N being the total number of layers), adifferential signal may be generated by subtracting an upsampled lowerlayer signal (e.g., layer n−1 signal) from a current layer n signal.This differential signal may be encoded. If respective video signalsrepresented by two layers, n1 and n2, have the same spatial resolution,corresponding downsampling and/or upsampling operations may be bypassed.A given layer n (e.g., 1≦n≦N), or a plurality of layers, may be decodedwithout using decoded information from higher layers.

Relying on the coding of a residual signal (e.g., a differential signalbetween two layers) for layers other than the base layer, for exampleusing the example SVC system of FIG. 1, may cause visual artifacts. Suchvisual artifacts may be due to, for example, quantization and/ornormalization of the residual signal to restrict its dynamic rangeand/or quantization performed during coding of the residual. One or morehigher layer encoders may adopt motion estimation and/or motioncompensated prediction as respective encoding modes. Motion estimationand/or compensation in a residual signal may be different fromconventional motion estimation, and may be prone to visual artifacts. Inorder to reduce (e.g., minimize) the occurrence of visual artifacts, amore sophisticated residual quantization may be implemented, for examplealong with a joint quantization process that may include bothquantization and/or normalization of the residual signal to restrict itsdynamic range and quantization performed during coding of the residual.Such a quantization process may increase complexity of the SVC system.

Multi-view video coding (MVC) may provide view scalability. In anexample of view scalability, a base layer bitstream may be decoded toreconstruct a conventional two-dimensional (2D) video, and one or moreadditional enhancement layers may be decoded to reconstruct other viewrepresentations of the same video signal. When such views are combinedtogether and displayed by a three-dimensional (3D) display, 3D videowith proper depth perception may be produced.

FIG. 2 depicts an example prediction structure for using MVC to code astereoscopic video with a left view (e.g., layer 1) and a right view(e.g., layer 2). The left view video may be coded with an I-B-B-Pprediction structure, and the right view video may be coded with aP-B-B-B prediction structure. As shown in FIG. 2, in the right view, thefirst picture collocated with the first I picture in the left view maybe coded as a P picture, and subsequent pictures in the right view maybe coded as B pictures with a first prediction coming from temporalreferences in the right view, and a second prediction coming frominter-layer reference in the left view. MVC may not support the singleloop decoding feature. For example, as shown in FIG. 2, decoding of theright view (e.g., layer 2) video may be conditioned on the availabilityof an entirety of pictures in the left view (e.g., layer 1), with one ormore (e.g., each) layer (e.g., view) having a respective compensationloop. An implementation of MVC may include high level syntax changes,and may not include block-level changes. This may ease implementation ofMVC. For example, MVC may be implemented by configuring referencepictures at the slice and/or picture level. MVC may support coding ofmore than two views, for instance by extending the example shown in FIG.2 to perform inter-layer prediction across multiple views.

MPEG frame compatible (MFC) video coding may provide a scalableextension to 3D video coding. For example, MFC may provide a scalableextension to frame compatible base layer video (e.g., two views packedinto the same frame), and may provide one or more enhancement layers torecover full resolution views. Stereoscopic 3D video may have two views,including a left and a right view. Stereoscopic 3D content may bedelivered by packing and/or multiplexing the two views into one frame,and by compressing and transmitting the packed video. At a receiverside, after decoding, the frames may be unpacked and displayed as twoviews. Such multiplexing of the views may be performed in the temporaldomain or the spatial domain. When performed in the spatial domain, inorder to maintain the same picture size, the two views may be spatiallydownsampled (e.g., by a factor of two) and packed in accordance with oneor more arrangements. For example, a side-by-side arrangement may putthe downsampled left view on the left half of the picture and thedownsampled right view on the right half of the picture. Otherarrangements may include top-and-bottom, line-by-line, checkerboard,etc. The arrangement used to achieve frame compatible 3D video may beconveyed by one or more frame packing arrangement SEI messages, forexample. Although such arrangement may achieve 3D delivery with minimalincrease in bandwidth consumption, spatial downsampling may causealiasing in the views and/or may reduce the visual quality and userexperience of 3D video.

Video applications, such as IPTV, video chat, mobile video, and/orstreaming video, may be deployed in heterogeneous environments.Heterogeneity may exist on the client side. Heterogeneity may exist in anetwork. An N-screen may comprise consuming video content on deviceswith varying screen sizes and/or display capabilities, including smartphones, tablets, PCs, and/or TVs. An N-screen may contribute toheterogeneity, for example, on the client side. Video may be transmittedacross the Internet, WiFi networks, mobile networks (e.g., 3G and/or4G), and/or any combination of these networks, for example, on thenetwork side. Scalable video coding may improve the user experienceand/or video quality of service. Scalable video coding may involveencoding a signal at the highest resolution. Scalable video coding mayinvolve enabling decoding from subsets of streams, for example,depending on the available network bandwidth and/or video resolutionused by certain applications and/or supported by the client device.Resolution may be characterized by a number of video parameters. Videoparameters may comprise one or more of the following: spatialresolution, temporal resolution, video quality, chroma format,bit-depth, complexity, view, color gamut, and/or aspect ratio, etc.Spatial resolution may comprise picture size. Temporal resolution maycomprise frame rate. Video quality may comprise subjective quality, suchas MOS, and/or objective quality, such as PSNR, SSIM or VQM. Chromaformat may comprise YUV420, YUV422 or YUV444, etc. Bit-depth maycomprise 8-bit video, 10-bit video, etc. Aspect ratio may comprise 16:9or 4:3, etc. HEVC scalable extension may support at least spatialscalability (e.g., the scalable bitstream may include signals at morethan one spatial resolution), quality scalability (e.g., the scalablebitstream may include signals at more than one quality level), and/orstandard scalability (e.g., the scalable bitstream may include a baselayer coded using H.264/AVC and one or more enhancement layers codedusing HEVC). In spatial scalability, the scalable bitstream may comprisesignals at one or more spatial resolution. In quality scalability, thescalable bitstream may comprise signals at one or more quality levels.In standard scalability, the scalable bitstream may comprise a baselayer coded using, for example, H.264/AVC, and one or more enhancementlayers coded using, for example, HEVC. Quality scalability may bereferred to as SNR scalability. View scalability may support 3D videoapplications. In view scalability, the scalable bitstream may includeboth 2D and 3D video signals.

A video coding system (e.g., a video coding system in accordance withscalable extensions of high efficiency video coding (SHVC)) may includeone or more devices that are configured to perform video coding. Adevice that is configured to perform video coding (e.g., to encodeand/or decode video signals) may be referred to as a video codingdevice. Such video coding devices may include video-capable devices, forexample, a television, a digital media player, a DVD player, a Blu-Ray™player, a networked media player device, a desktop computer, a laptoppersonal computer, a tablet device, a mobile phone, a video conferencingsystem, a hardware and/or software based video encoding system, or thelike. Such video coding devices may include wireless communicationsnetwork elements, such as a wireless transmit/receive unit (WTRU), abase station, a gateway, or other network elements.

Scalable enhancements of HEVC may be discussed herein. One or moretargets may have been established, for example, for spatial scalability.The targets of 25% bit rate reduction for 2× spatial scalability and 50%bit rate reduction for 1.5× spatial scalability may be achieved, forexample, compared to using non-scalable coding, measured for higherresolution video. Scalability may be used, for example, to broaden theuse cases for scalable HEVC. Scalability may refer to the type ofscalability when the base layer may be encoded with H.264/AVC, or MPEG2,while the one or more enhancement layers may be encoded using, forexample, HEVC. Scalability may provide backward compatibility for legacycontent that may be encoded using H.264/AVC, or MPEG2, and enhance thequality of the legacy content with one or more enhancement layersencoded with HEVC, that may provide better coding efficiency.

3D scalable video coding technique may be referred to as 3D video codingor 3DV. 3DV may be discussed herein. 3DV may develop various flavors ofview scalability that may be targeted for autostereoscopic applications.Autostereoscopic displays and applications may allow or enable people toexperience 3D without the cumbersome glasses. To achieve a suitable orgood 3D experience without glasses, more than two views may be providedand/or used. Coding many views (e.g., such as 9 views or 10 views) maybe expensive. 3DV may provide and/or use a hybrid approach of coding afew views (e.g., 2 or 3 views) with relatively large disparity togetherwith the depth maps that may provide depth information of the views. Atthe display side, the coded views and depth maps may be decoded, and theremaining views may be generated using the decoded views and their depthmaps using, for example, view synthesis technologies. 3DV may considervarious methods to code the views and the depth maps, for example,coding the views and the depth maps using a combination of differenttechniques, such as H.264/AVC, MVC and HEVC, including coding the baselayer with one technique (e.g., H.264/AVC) and coding one or moreenhancement layers with another technique (e.g., HEVC). 3DV may providea menu of different options from which applications may choose.

Table 1 may summarize an example of the different types of scalabilitiesdiscussed herein. At the bottom of Table 1, bit-depth scalability andchroma format scalability may be tied to video formats (e.g., higherthan 8-bit video and/or chroma sampling formats higher than YUV4:2:0)used by professional video applications. Bit-depth scalability andchroma format scalability may be utilized. Aspect ratio scalability andcolor gamut scalability may be provided and/or used as desirablescalability (e.g., but may not be currently provided, used, and/orplanned for the first phase of scalable HEVC development).

FIG. 3 illustrates a comparison between BT.709 (HDTV) and BT.2020(UHDTV) in a CIE color definition. With advanced display technologies,ultra-high definition TV (UHDTV) may support larger resolution, largerbit-depth, higher frame-rate, and wider color gamut compared to the HDTVspecification (e.g., BT.709). The user experience may be greatlyimproved due to the high fidelity quality that BT.2020 may provide.UHDTV may support up to 4K (3840×2160) and 8K (7680×4320) resolution,with the frame-rate being up to 120 Hz, and the bit-depth of picturesamples being 10 bits or 12 bits. The color space of UHDTV 310 may bedefined by BT.2020. The color space of UHDTV 320 may be defined byBT.790. The volume of colors rendered in BT.2020 310 may be broader thanthe volume of color space in HDTV 320 (e.g., BT.709), which may meanmore visible color information may be rendered using the UHDTVspecification.

TABLE 1 Examples of different types of scalabilities Scalability ExampleView scalability 2D→3D (2 or more views) Spatial scalability 720 p→1080p Quality (SNR) 35 dB→38 dB scalability Temporal scalability 30 fps→60fps Standards scalability H.264/AVC→HEVC Bit-depth scalability 8-bitvideo → 10-bit video Chroma format YUV4:2:0→YUV4:2:2, scalabilityYUV4:4:4 Aspect ratio scalability 4:3→16:9 Color gamut scalabilityBT.709(HDTV) -> BT.2020(UHDTV)

Color gamut scalability. Color gamut scalable (CGS) coding may bemulti-layer coding where two or more layers may have different colorgamut and bit-depth. For example, as shown in Table 1, in a 2-layerscalable system, the base layer may be a HDTV color gamut as defined inBT.709 and the enhancement layer may be a UHDTV color gamut as definedin BT.2020. P3 color gamut is a color gamut that may be used. The P3color gamut may be used in digital cinema applications. The inter-layerprocess in CGS coding may use color gamut conversion techniques toconvert a base layer color gamut to an enhancement layer color gamut.After color gamut conversion may be applied, the inter layer referencepictures generated may be used to predict the enhancement layerpictures, for example, with better or improved accuracy.

FIG. 4A and FIG. 4B may depict an example of a visual difference to theend users between the BT.709 color gamut and the BT.2020 color gamutrespectively. In FIG. 4A and FIG. 4B, the same content may be colorgraded twice using a different color gamut. For example, the content inFIG. 4A may be color graded in BT.709 and rendered/displayed on a BT.709display. The content in FIG. 4B may be color graded in BT.2020 andrendered/displayed on BT.709 display. As shown, the color differencebetween the two images may be different.

FIG. 5 may illustrate an example color gamut scalability (CGS) codingwith picture level interlayer prediction. In an example embodiment, FIG.4A may be coded in the base layer and FIG. 4B may be coded in theenhancement layer. Additional inter-layer processing may be providedand/or used to improve the enhancement layer coding efficiency, forexample, using the CGS coding system in FIG. 5. Color gamut conversionmay be used in inter-layer processing for CGS. Through the use of colorgamut conversion, the colors in BT.709 space may be translated into theBT.2020 space. The colors in BT.709 space may be used to moreeffectively predict enhancement layer signal in the BT.2020 space.

As shown in FIG. 5, the base layer (BL) video input 530 may be an HDvideo signal, and the enhancement layer (EL) video input 502 may be aUHD video signal. The HD video signal 530 and the UHD video signal 502may correspond to each other, for example by one or more of: one or moredownsampling parameters (e.g., spatial scalability); one or more colorgrading parameters (e.g., color gamut scalability), or one or more tonemapping parameters (e.g., bit depth scalability) 528.

The BL encoder 518 may include, for example, a high efficiency videocoding (HEVC) video encoder or an H.264/AVC video encoder. The BLencoder 518 may be configured to generate the BL bitstream 532 using oneor more BL reconstructed pictures (e.g., stored in the BL DPB 320) forprediction. The EL encoder 504 may include, for example, an HEVCencoder. The EL encoder 504 may include one or more high level syntaxmodifications, for example, to support inter-layer prediction by addinginter-layer reference pictures to the EL DPB. The EL encoder 504 may beconfigured to generate the EL bitstream 508 using one or more ELreconstructed pictures (e.g., stored in the EL DPB 506) for prediction.

One or more reconstructed BL pictures in the BL DPB 520 may beprocessed, at inter-layer processing (ILP) unit 522, using one or morepicture level inter-layer processing techniques, including one or moreof upsampling (e.g., for spatial scalability), color gamut conversion(e.g., for color gamut scalability), or inverse tone mapping (e.g., forbit depth scalability). The one or more processed reconstructed BLpictures may be used as reference pictures for EL coding. Inter-layerprocessing may be performed based on enhancement video information 514received from the EL encoder 504 and/or the base video information 516received from the BL encoder 518. This may improve EL coding efficiency.

At 526, the EL bitstream 508, the BL bitstream 532, and the parametersused in inter-layer processing such as ILP information 524, may bemultiplexed together into a scalable bitstream 512. For example, thescalable bitstream 512 may include an SHVC bitstream.

The model parameters for color gamut conversion may be different fordifferent content, for example, even when the BL color gamut and the ELcolor gamut may be fixed (e.g., BL may be in 709 and may be EL in 2020).These parameters may depend on the color grading process during postproduction in content generation where the colorists may apply differentgrading parameters to different spaces and/or different content toreflect his or her artistic intent. The input video for color gradingmay include high fidelity pictures. In a scalable coding system, codingof the BL pictures may introduce quantization noise. With codingstructures such as the hierarchical prediction structure, the level ofquantization may be adjusted per picture and/or per group of pictures.The model parameters generated from color grading may not besufficiently accurate for coding purposes. In an embodiment, it may bemore effective for the encoder to compensate the coding noise byestimating the model parameters at any point. The encoder may estimatethe model parameters per picture or per groups of pictures. These modelparameters, for example, generated during color grading process and/orby the encoder, may be signaled to the decoder at the sequence and/orpicture level so the decoder may perform the same color gamut conversionprocess during inter-layer prediction.

Color gamut conversion examples may include, but are not limited to,linear or piece-wise linearc color conversions. In the film industry, a3D Look-up Table (3D LUT) may be used for color gamut conversion fromone color gamut method or technique to another. Additionally, 3D LUT forCGS coding may be provided and/or used. FIG. 5 depicts an example CGScoding scheme with picture level inter-layer prediction (ILP). The ILPincludes color gamut conversion from base layer (BL) color gamut toenhancement layer (EL) color gamut, upsampling from BL spatialresolution to EL spatial resolution, and/or inverse tone mapping from BLsample bit-depth to EL sample bit-depth.

FIG. 6 illustrates an example 3D Look-up Table for 8-bit YUV signal.FIG. 7 illustrates an example weight calculation in tri-linear ortetrahedral interpolation. As described herein, a color conversionmodel, such as a 3D LUT, may be used for a color gamut conversion. Forexample, (y, u, v) may be denoted as the sample triplet in the colorgamut of the base layer, and (Y, U, V) as the triplet in EL color gamut.In 3D LUT, the range of BL color space may be segmented into equaloctants, for example, as shown in FIG. 6.

The input of the 3D LUT may be (y, u, v) in the BL color gamut and theoutput of 3D LUT may be the mapped triplet (Y, U, V) in EL color gamut.For example, referring to FIG. 7, the input may be index (y, u, v) thatresides within the octant 700. During a conversion process, if the input(y, u, v) overlaps with one of the vertices of octants, the output (Y,U, V) may be derived by referencing one of the 3D LUT entries directly,for example, the component (y, u, v) that overlaps its respectivevertex. If the input (y, u, v) (e.g., or any one of the components ofthe input) lie inside an octant (e.g., but not on one of its vertices),such as the index (y, u, v) of FIG. 7, an interpolation process may beapplied. For example, trilinear and/or tetrahedral interpolations andmethods for performing the same may be applied. Trialinear-interpolationmay be applied with its nearest 8 vertices, for example, as shown inFIG. 7. The trilinear-interpolation may be carried out using one or moreof the following equations:

$\begin{matrix}{Y = {K \times {\sum\limits_{{i = 0},1}{\sum\limits_{{j = 0},1}{\sum\limits_{{k = 0},1}{{s_{i}(y)} \times {s_{j}(u)} \times {s_{k}(v)} \times L\; U\;{{{{T\left\lbrack y_{i} \right\rbrack}\left\lbrack u_{j} \right\rbrack}\left\lbrack v_{k} \right\rbrack}.Y}}}}}}} & (1) \\{U = {K \times {\sum\limits_{{i = 0},1}{\sum\limits_{{j = 0},1}{\sum\limits_{{k = 0},1}{{s_{i}(y)} \times {s_{j}(u)} \times {s_{k}(v)} \times L\; U\;{{{{T\left\lbrack y_{i} \right\rbrack}\left\lbrack u_{j} \right\rbrack}\left\lbrack v_{k} \right\rbrack}.U}}}}}}} & (2) \\{{V = {K \times {\sum\limits_{{i = 0},1}{\sum\limits_{{j = 0},1}{\sum\limits_{{k = 0},1}{{s_{i}(y)} \times {s_{j}(u)} \times {s_{k}(v)} \times L\; U\;{{{{T\left\lbrack y_{i} \right\rbrack}\left\lbrack u_{j} \right\rbrack}\left\lbrack v_{k} \right\rbrack}.V}}}}}}}{K = \frac{1}{\left( {y_{1} - y_{0}} \right) \times \left( {u_{1} - u_{0}} \right) \times \left( {v_{1} - v_{0}} \right)}}} & (3)\end{matrix}$Referring to Equations (1)-(3) and FIG. 7, for example, (y_(i), u_(j),v_(k)) may represent the vertices of the BL color gamut (i.e., inputs to3D LUT). LUT[y_(i)][u_(j)][v_(k)] may represent the vertices of the ELcolor gamut (i.e., outputs of 3D LUT at the entry (y_(i), u_(j),v_(k))). LUT[y_(i)][u_(j)][v_(k)]. Y, LUT[y_(i)][u_(j)][v_(k)]. U,LUT[y_(i)][u_(j)][v_(k)]. V may represent the Y, U, and V components ofthe vertex LUT[y_(i)][u_(j)][v_(k)], respectively. i, j, k={0, 1}, ands₀(y)=y₁−y, s₁(y)=y−y₀, s₀(u)=u₁−u, s₁(u)=u−u₀, s₀(v)=v₁−v, s₁(v)=v−v₀may be the weights that are applied, for example, as shown in FIG. 7.

FIG. 8 illustrates an example tetrahedral interpolation. FIG. 9A, FIG.9B, FIG. 9C, FIG. 9D, FIG. 9E and FIG. 9F illustrate types oftetrahedrons to encompass an interpolating point. Tetrahedralinterpolation may use four vertices of the tetrahedron including apoint, P(y, u, v), to be interpolated for calculation. The input point P(i.e., P(y, u, v)) in FIG. 8 may be enclosed inside the tetrahedronwhose vertices may be P0, P1, P5, P7. The tetrahedral interpolation maybe calculated in Equation (4)(5)(6) for each component. There may be sixpossible choices of the tetrahedron that may comprise the point P to beinterpolated. FIGS. 9A-9F may show or list the six possible cases. In anexample, the vertices P0 and P7 may be included in the tetrahedron.

$\begin{matrix}{Y = {{T_{y} \times \left( {{\left( {{y\; 1} - {y\; 0}} \right) \times L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.Y}} + {{dy} \times \left( {{L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.Y}} - {L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.Y}}} \right)}} \right)} + {T_{u} \times {du} \times \left( {{L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.Y}} - {L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.Y}}} \right)} + {T_{v} \times {dv} \times \left( {{L\; U\;{{T\left\lbrack P_{7} \right\rbrack}.Y}} - {L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.Y}}} \right)}}} & (4) \\{U = {{T_{y} \times \left( {{\left( {{y\; 1} - {y\; 0}} \right) \times L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.U}} + {{dy} \times \left( {{L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.U}} - {L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.U}}} \right)}} \right)} + {T_{u} \times {du} \times \left( {{L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.U}} - {L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.U}}} \right)} + {T_{v} \times {dv} \times \left( {{L\; U\;{{T\left\lbrack P_{7} \right\rbrack}.U}} - {L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.U}}} \right)}}} & (5) \\{{V = {{T_{y} \times \left( {{\left( {{y\; 1} - {y\; 0}} \right) \times L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.V}} + {{dy} \times \left( {{L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.V}} - {L\; U\;{{T\left\lbrack P_{0} \right\rbrack}.V}}} \right)}} \right)} + {T_{u} \times {du} \times \left( {{L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.V}} - {L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.V}}} \right)} + {T_{u} \times {du} \times \left( {{L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.V}} - {L\; U\;{{T\left\lbrack P_{1} \right\rbrack}.V}}} \right)} + {T_{v} \times {dv} \times \left( {{L\; U\;{{T\left\lbrack P_{7} \right\rbrack}.V}} - {L\; U\;{{T\left\lbrack P_{5} \right\rbrack}.V}}} \right)}}}\mspace{79mu}{{T_{y} = \frac{1}{\left( {y_{1} - y_{0}} \right)}},{T_{u} = \frac{1}{\left( {u_{1} - u_{0}} \right)}},{T_{v} = \frac{1}{\left( {v_{1} - v_{0}} \right)}}}} & (6)\end{matrix}$

3D LUT may be estimated by the encoder, for example, using an originalsignal in one color space and the corresponding signal in another colorspace. For example, a Least Square (LS) estimation method may be used toestimate a 3D LUT, for example, if a 3D LUT interpolation technique orprocess is linear. A gradient descent based iterative technique may beused for estimation. As described herein, a 3D LUT estimation may beperformed with a LS estimation method.

There may be challenges for 3D LUT estimation with LS. For example, thescale of 3D LUT parameters that may be estimated may be large. In FIG.6, the sample bit-depth may be 8 bits. If the unit octant size is16×16×16, there may be 17×17×17 entries in the 3D LUT table. One or more(e.g., each) entry of the 3D LUT may comprise three components. Theremay be 4913 (17×17×17) unknown parameters of each component. Such alarge scale linear system estimation may use a large amount of memoryand may invoke a large number of computations.

The 3D LUT may not be fully used for color gamut conversion of a givenvideo input. For example, in a statistical analysis of one or more testsequences used in core experiments of color gamut scalability, apercentage of used entries in 3D LUT may be less than 20%. In such anembodiment, a LS estimation method may not be able to be directlyapplied because there may be one or more entries that may not bemeasured.

A distribution of BL pixels may not be even in a 3D color space. Forexample, such BL pixels may cluster around some colors (e.g., majorcolors) and may be distributed sparsely around other colors. Thisunbalanced characteristic may be related to a stability of the LSestimation as may be described herein.

FIG. 10 illustrates an example of the luma and chroma sample locationsof a YUV 4:2:0 video. A phase of luma and chroma of an input video maynot be aligned. To estimate and to apply a 3D LUT for one or more (e.g.,each) component, the triplet formed by three components may be used. Atriplet may refer to a luma component and two chroma components that areat the same sampling location (e.g., a luma component, a red differencechroma component, and a blue difference chroma component at the samesampling location). The misalignment of the luma and chroma samplelocations may affect the precision of 3D LUT interpolation.

To address one or more of such challenges, systems and/or methods may beprovided to improve 3D LUT estimation. For example, a BT.709 to BT.2020color gamut conversion may be described herein. For example, the inputsignal in 3D LUT estimation may be the BT.709 compressed/uncompressedvideo, and the output signal may be BT.2020 video (e.g., which may bethe training reference or target). Equation (7) may be used to describethe color gamut conversion process with 3D LUT.z _(i)(c)=f _(P(c))(x _(i)), iε[0,N−1]  (7)where * may denote an input signal in the form of triplet (y, u, v) inBT.709. z(c) may be the output signal of component c where c may be Y, Uor V in BT.2020. P(c) may be the parameters of component c to beestimated. P(c) may be the 3D LUT output of component c. f_(P(c)) may bethe interpolation function. f_(P(c)) may be a linear function, such astrilinear or tetrahedral as described herein. i may be the index ofinput pixel. N may be the total number of input pixels. Rewritten in theform of matrices it may be as follows:z _(i)(c)={right arrow over (w)} _(i)(c)*P(c), iε[0,N−1]  (8)where * in Equation (8) may be matrix multiplication. {right arrow over(w)}_(i)(c) may be the weighting vector for the i-th input pixel.w_(i,j) may be the weight of the j-th output entry of 3D LUT for thei-th input pixel. In an example, w_(i,j) may be calculated according toEquation (1)-(3) for trilinear interpolation and Equation (4)-(6) fortetrahedral interpolation. The weighting vector may be as follows in anexample:{right arrow over (w)} _(i)(c)=[w _(i,0) . . . w _(i,M−1)], iε[0,N−1]P(c) may be the parameter vector to be estimated, which may be theoutput entries of 3D LUT, and may be as follows:P(c)=[p ₀ . . . p _(M−1)]M may be the number of 3D LUT output entries. For example M may be 4913for 17×17×17 sized 3D LUT. In an example, the component c may be omittedin the following equations as the 3D LUT of one or more (e.g., each)component may be estimated independently. Aggregating Equation (8) forone or more (e.g., all) pixels, the following may be defined orprovided:

$\begin{matrix}{{Z = {W*P}}{Z = \begin{bmatrix}z_{0} & \ldots & z_{N - 1}\end{bmatrix}^{T}}} & (9) \\{W = \begin{bmatrix}w_{0,0} & w_{0,1} & \ldots & w_{0,{M - 1}} \\\vdots & \vdots & \ddots & \vdots \\w_{{N - 1},0} & w_{{N - 1},1} & \ldots & w_{{N - 1},{M - 1}}\end{bmatrix}} & (10)\end{matrix}$With Least Square estimation, the solution may be as follows:P=H ⁻¹*(W ^(T) *Z)  (11)H=(W ^(T) *W)  (12)where H may be the auto-correlation matrix.

3D LUT estimation may be described herein. For example, for an inputvideo signal such as BT.709, 3D LUT entries (e.g., 20% of 3D LUTentries) may be used in color conversion with 3D LUT. This may mean thematrix W in Equation (10) may be sparse and one or more of its elementsmay be zeros. An auto-correlation matrix H may be defined in Equation(12). The auto-correlation matrix H may be sparse. The auto-correlationmatrix H may not be inversible. The solution in Equation (11) may not beavailable for the auto-correlation matrix H. In an example, the matrix Wmay be compacted by considering referenced entries of 3D LUT. To compactthe matrix, the input pixels (y, u, v) of the input video may bescanned. The 3D LUT vertices may be masked, for example, if the verticesmay be used in a 3D LUT interpolation process. The compact parameter setP′ may be determined, calculated, or generated by removing the unusedvertices. A mapping from P′ to P that may be used to reconstruct P afterP′ may be estimated and/or built, for example, asP′=compact(P)

W′ and H′ may be calculated using the compacted P′, for example, whereunused vertices may have been removed. The solution may be defined as:P′=H′ ⁻¹*(W′ ^(T) *Z)  (13)H′=(W′ ^(T) *W′)  (14)

3D LUT estimation may reduce the sparsity of the matrix W. The memorythat may be used to store the auto-correlation matrix H for the 3D LUTestimation may be reduced, for example, after compaction since the sizeof H′ may be smaller than H.

As described herein, a color distribution of an input video may not beeven. For example, pixels may have similar colors. Colors with highoccurrence rates may be major colors. This may cause an unbalanceproblem with W′. For example, elements in W′ may correspond to majorcolors may have large values. Other elements in W′ may correspond tocolors that may not occur often (e.g., relatively often or rarely) mayhave low or smaller values. The result may be that the dynamic range ofelements in the auto correlation matrix H′ may be large, which may causethe inversion process of H′ to become unstable. The estimation of P′ maybecome unstable. To reduce such a problem, a constraint may be providedand/or used to establish a trade-off between accurate estimation resultsand stability of the estimation process. For example,H′=(W′ ^(T) *W′)+λI, λ≧0  (15)where I may be a unary matrix, and λ may be the factor to balancebetween the estimation accuracy and stability of the process. A larger λmay mean more bias may be put on the stability of the method or process.The value of λ may be determined based on the extent of unbalance in W′.

The original parameter vector P may be obtained by mapping the estimatedvertices from P′ to P, for example, after the compact parameter vectorP′ may be estimated. For example,P=decompact(P′)  (16)

The unused vertices in P may be filled using the corresponding verticesin P′, for example, using the interpolation process (e.g., trilinear ortetrahedral) in 3D LUT coding.

As described herein, FIG. 10 illustrates the phase shift between lumaand chroma components for 4:2:0 chroma format. A luma and chroma phasealignment in 3D LUT estimation may be described herein. For example,from trilinear interpolation in Equations (1)-(3) or tetrahedralinterpolation in Equations (4)-(6), a 3D LUT interpolation for one ormore (e.g., each) output component may use three input components of aninput signal.

As shown in FIG. 10 and described herein, in an example, the lumacomponent sampling locations and chroma component sampling locations maynot be aligned. FIG. 10 may depict a 4:2:0 chroma format. Although thecomponent conversion may be described with respect to FIG. 10 and/or a4:2:0 chroma format, the examples described herein may be utilized for a4:1:0 chroma format, a 4:2:2:0 chroma format, a 4:4:4 chroma format,etc. Although FIG. 10 is described with reference to the YCbCr format,other color formats may be used.

In FIG. 10, sample locations L0-L15 may indicate sampling locations of aluma component. In FIG. 10, L may indicate a luma component and thenumber (e.g., 0-15) may indicate the sampling location. Samplinglocations C0-C3 may indicate sampling locations of one or more (e.g.,two) overlapping chroma components (e.g., a red difference chromacomponent and a blue difference chroma component). In FIG. 10, C mayindicate one or more (e.g., two) overlapping chroma components (e.g., ared difference chroma component and a blue difference chroma component)and the number (e.g, 0-3) may indicate the sampling location.

FIG. 10 may be a grid with an x- and y-axes, where the x-axis may be ahorizontal axis and the y-axis may be a vertical axis. The lumacomponent at sampling locations L0-L15 may have an x coordinate and a ycoordinate. The one or more (e.g., two) overlapping chroma components(e.g., a red difference chroma component and a blue difference chromacomponent) at sampling locations C0-C3 may have an x coordinate and a ycoordinate.

Misalignment of sampling locations may reduce the accuracy of 3D LUTestimation. For example as shown in FIG. 10, the luma component samplinglocations, L0-L15, do not overlap the chroma component samplinglocations, C0-C3. Misalignment of sampling locations may be present inchroma formats, such as 4:2:0 or 4:2:2, where the chroma components aresubsampled in both directions (e.g., 4:2:0, in which there are one reddifference chroma component sample and one blue difference chromacomponent sample for every four luma components) or in the horizontaldirection (e.g. 4:2:2). As a result of the chroma subsampling process,the sample positions of the luma and the chroma positions may becomemisaligned.

For luma component interpolation, a plurality of sampling locations ofone or more chroma components (e.g., a red difference chroma componentand/or blue difference chroma component) may be used to align the chromacomponents to the luma component sample location. For a chroma componentinterpolation, one or more sampling locations of the luma component maybe used to align the luma component to the chroma component samplinglocation. Once aligned, a color component conversion model, such as a 3DLUT, may be used to translate a component (e.g., luma or chroma) fromone color space to another. Translating a component from one color spaceto another color space may be determining the component in the secondcolor space, for example, using the component in the first color space(e.g., at a particular sampling location).

The video coding device may receive a scalable bitstream. The scalablebitstream may comprise a base layer and an enhancement layer. The baselayer may comprise the picture and the base layer may be associated withthe first color space. The enhancement layer may be associated with thesecond color space.

The input for 3D LUT conversion may signal components (e.g., (y, u, v))in one color space (e.g., BT.709), and the output of 3D LUT conversionmay be the components (e.g., (Y, U, V)) in another color space (e.g.,BT.2020). For chroma component conversion, the luma component y may beadjusted to y′ to align to the chroma component sampling location. Theinterpolation filter may be Equations (17)-(18). The input for 3D LUTconversion of chroma component may be (y′, u, v), and the output may beU or V. The interpolation filter may be a 2-tap filter [1, 1], a 4-tapfilter, and/or the like.

A video coding device may receive a picture associated with a firstcolor space. The picture may comprise a first chroma component at afirst sampling location, a second chroma component at the first samplinglocation, a luma component at a second sampling location, a lumacomponent at a third sampling location, a luma component at a fourthsampling location, and a luma component at a fifth sampling location.The video coding device may apply a first interpolation filter to two ormore of the luma component at the second sampling location, the lumacomponent at the third sampling location, the luma component at thefourth sampling location, and the luma component at the fifth samplinglocation to determine the luma component at the first sampling location,wherein the luma component at the first sampling location is associatedwith the first color space. The video coding device may apply a colorconversion model to the first chroma component at the first samplinglocation, the second chroma component at the first sampling location,and to the luma component at the first sampling location to translatethe first chroma component at the first sampling location to a secondcolor space. The video coding device may apply the color conversionmodel to the first chroma component at the first sampling location, thesecond chroma component at the first sampling location, and to the lumacomponent at the first sampling location to translate the second chromacomponent at the first sampling location to the second color space. Thefirst chroma component and/or the second chroma component may be a reddifference chroma component and/or a blue difference chroma component,for example, if the YCbCr format is used. The first chroma componentand/or the second chroma component may be a green difference chromacomponent and/or an orange difference chroma component, for example, ifthe YCgCo format is used. It should be noted that the descriptionsherein may be applicable to color spaces represented in other formats.

As shown in FIG. 10, for example, one or more interpolation filters(e.g., those shown in Equations (17)-(18)) may be used to align the lumacomponent to the sampling location of a misaligned chroma component.Once aligned, a conversion model, such as a 3D LUT, may be used toconvert the chroma component from a first color space to a second colorspace. The input for 3D LUT conversion of a chroma component may be (y′,u, v), for example if the chroma components have the same samplinglocations, and where y′ is the adjusted luma component (e.g., the lumacomponent at the sampling location that overlaps with the samplinglocation of the chroma components u, v). The components (y′, u, v) maybe associated with the first color space. The output of the 3D LUT maybe U or V, which may refer to a chroma component, U or V, in the secondcolor space.

Interpolation filters, (e.g., those shown in Equations (17)-(18)) may beused to align the luma component to the sampling location of the chromacomponent such that the conversion model may be used. For example, theluma component at a sampling location of a chroma component (e.g.,sampling location C0) may be determined by applying an interpolationfilter using the luma component at two or more luma sampling locations(e.g., sampling locations L0, L1, L4, and/or L5), for example, asdescribed with reference to Equations (17)-(18). The sampling locationof a chroma component may comprise two or more chroma components, forexample, a red difference chroma component C_(r) 0 and correspondingblue difference chroma component C_(b) 0). The luma component at thesampling location C0 and chroma components at the sampling location C0may be used to translate the chroma component at the location C0 from afirst color space to a second color space.

For example, as discussed herein, when converting a chroma componentfrom one color space to another, the value of the luma component at thechroma component sampling location may be determined To determine valueof the luma component at a sampling location of a chroma component(e.g., sampling location C0), a video coding device may use a four-tapinterpolation filter or a two-tap interpolation filter. The video codingdevice may determine which interpolation filter to use based on thesampling location of the chroma component on the x-y axis in FIG. 10.For example, the video coding device may determine the x and ycomponents of the chroma component at a sampling location. The videocoding device may then divide the x coordinate of the chroma componentsampling location by two, and the video coding device may divide the ycoordinate of the chroma component sampling location by two. If theremainder of the division of the x coordinate by two is one, and theremainder of the division of the y coordinate by two is one, the videocoding device may utilize the interpolation filter in Equation (17) orEquation (18) to determine the luma component at a sampling location ofa chroma component. If the remainder of the division of the x coordinateby two is zero, and the remainder of the division of the y coordinate bytwo is one, the video coding device may utilize the interpolation filterin Equation (17) or Equation (18) to determine the luma component at asampling location of a chroma component. If the remainder of thedivision of the x coordinate by two is one, and the remainder of thedivision of the y coordinate by two is zero, the video coding device mayutilize the interpolation filter in Equation (17) or Equation (18) todetermine the luma component at a sampling location of a chromacomponent. If the remainder of the division of the x coordinate by twois zero, and the remainder of the division of the y coordinate by two iszero, the video coding device may utilize the interpolation filter inEquation (17) or Equation (18) to determine the luma component at asampling location of a chroma component. A video coding device may useEquations (17)-(18) interchangeably to determine the value (e.g., align)the luma component at a sampling location of a chroma component.

For example, the luma component at the sampling location C0 may bedetermined using a four-tap filter, for example, as shown in Equation(17):L(C0)=((L0+L4)*3+(L1+L5)+4)>>3  (17)where >>3 may mean the sum of ((L0+L4)*3+(L1+L5)+4) is divided by 2³and/or >>3 is calculated using right shift by three. If the sum of((L0+L4)*3+(L1+L5)+4) is not an integer, the decimal may be disregardedprior to dividing the sum by 2³. In Equation 17, to determine the lumacomponent at the sampling location C0, a video coding device may applyan interpolation filter in which the luma component at sampling locationL0 is added to the luma component at a different sampling location L4 todetermine a sum. The video coding device may then multiply the sum bythree, and add the multiplied sum to the luma component at samplinglocation L1, the luma component at sampling location L5 and four todetermine a final sum. An integer sum of the final sum may bedetermined. The video coding device may then divide this integer sum by8 to determine the luma component at the sampling location C0. The lumacomponent at the sampling locations C1, C2, and C3 may be determinedusing Equation 17 with the appropriate luma components.

The luma component at the sampling location C0 may be determined using atwo-tap filter. An example of a two-tap filter that may be used isprovide in Equation (18):L(C0)=(L0+L4+1)>>1  (18)where >>1 may mean the sum of (L0+L4+1) is divided by 2¹ and/or >>1 iscalculated using right shift by one. If the sum of (L0+L4+1) is not aninteger, the decimal may be disregarded prior to dividing the sum by 2¹.In Equation 18, to determine the luma component for the samplinglocation C0, a video coding device may apply a two-tap interpolationfilter in which the luma component at a sampling location L0 is added tothe luma component at a different sampling location L4 and one todetermine a sum. An integer sum of the final sum may be determined. Thevideo coding device may then divide the integer value of the sum by twoto determine the luma component at the sampling location C0. The lumacomponent at the sampling locations C1, C2, and C3 may be determinedusing Equation 18 with the appropriate luma components.

The video coding device may translate (e.g., determine) a chromacomponent at the sampling location C0 in a second color space using theluma component at the sampling location C0 in the first color space andboth of the chroma components at the sampling location C0 in the firstcolor space using a conversion model, for example, a 3D LUT as describedherein. As noted, the luma component at the sampling location C0 may bedetermined using an interpolation filter, for example, as shown inEquation (17) or (18).

A video coding device may receive a picture associated with a firstcolor space. The picture may comprise a luma component at a firstsampling location, a first chroma component at a second samplinglocation, a second chroma component at the second sampling location, thefirst chroma component at a third sampling location, the second chromacomponent at the third sampling location, the first chroma component ata fourth sampling location, the second chroma component at the fourthsampling location, the first chroma component at a fifth samplinglocation, and the second chroma component at the fifth samplinglocation. The video coding device may apply an interpolation filter totwo or more of the first chroma component at the second samplinglocation, the first chroma component at the third sampling location, thefirst chroma component at the fourth sampling location, and the firstchroma component at the fifth sampling location to determine the firstchroma component at the first sampling location, wherein the firstchroma component at the first sampling location is associated with thefirst color space. The video coding device may apply the interpolationfilter to two or more of the second chroma component at the secondsampling location, the second chroma component at the third samplinglocation, the second chroma component at the fourth sampling location,and the second chroma component at the fifth sampling location todetermine the second chroma component at the first sampling location,wherein the second chroma component at the first sampling location isassociated with the first color space. The video coding device may applya color conversion model to the luma component at the first samplinglocation, the first chroma component at the first sampling location, andthe second chroma component at the first sampling location to translatethe luma component at the first sampling location to a second colorspace. The first chroma component and/or the second chroma component maybe a red difference chroma component and/or a blue difference chromacomponent

As shown in FIG. 10, for example, one or more interpolation filters(e.g., those shown in Equations (19)-(22)) may be used to align one ormore chroma components to the sampling location of a misaligned lumacomponent. Once aligned, a conversion model, such as a 3D LUT, may beused to convert the luma component from a first color space to a secondcolor space. The input for 3D LUT conversion for the luma component maybe (y, u′, v′), where u′ and v′ are the adjusted chroma components(e.g., the chroma components at the sampling location that overlaps withthe sampling location of the luma component y). The components (y, u′,v′) may be associated with the first color space. The output of the 3DLUT is Y, which may refer to the luma component in the second colorspace.

Interpolation filters (e.g., those shown in Equations (19)-(22)) may beused to align a chroma component to the sampling location of the lumacomponent such that the conversion model may be used. For example, achroma component at a sampling location of a luma component (e.g.,sampling location L4, L5, L8, and/or L9) may be determine by applying aresampling filter using the chroma component at two or more samplinglocations (e.g., sampling locations C0, C1, C2, and/or C3). As such, aresampled value of a component (e.g., a value of the component at adifferent sampling location) may be determined using the component at aplurality of other sampling locations. For example, the luma componentat the sampling locations L4, L5, L8, and/or L9 in FIG. 10 may beinterpolated using a 3D LUT. To interpolate the luma component at thesampling locations L4, L5, L8, and/or L9, chroma components (e.g., u, v)at the sampling locations L4, L5, L8, and/or L9 may be determined. Thechroma components at the sampling locations L4, L5, L8, and L9 may bederived using one or more resampling filters (e.g., Equations(19)-(22)), for example, as described herein. The luma component at thesampling location L4, L5, L8, and/or L9 and chroma components at thesampling location L4, L5, L8, and/or L9 may be used to translate theluma component at the location L4, L5, L8, and/or L9 from a first colorspace to a second color space.

For example, as discussed herein, when converting a luma component fromone color space to another, the value of the chroma component (e.g., thered difference chroma component and/or the blue difference chromacomponent) at the luma component sampling location may be determined Todetermine value of the chroma component at a sampling location of a lumacomponent (e.g., sampling location L0, L1, L4, L5), a video codingdevice may use a four-tap interpolation filter or a two-tapinterpolation filter. The video coding device may determine whichinterpolation filter to use based on the sampling location of the lumacomponent on the x-y axis in FIG. 10. For example, the video codingdevice may determine the x and y components of the luma component at asampling location. The video coding device may then divide the xcoordinate of the luma component sampling location by two, and the videocoding device may divide the y coordinate of the luma component samplinglocation by two. If the remainder of the division of the x coordinate bytwo is zero, and the remainder of the division of the y coordinate bytwo is one, the video coding device may utilize the interpolation filterin Equation (19) to determine the chroma component (e.g., red differencechroma component and/or blue difference chroma component) at a samplinglocation of a luma component. As shown in FIG. 10, Equation (19) may beutilized to determine the chroma component (e.g., red difference chromacomponent and/or blue difference chroma component) at the luma componentsampling locations L4, L6, L12 and L14. If the remainder of the divisionof the x coordinate by two is one, and the remainder of the division ofthe y coordinate by two is one, the video coding device may utilize theinterpolation filter in Equation (20) to determine the chroma component(e.g., red difference chroma component and/or blue difference chromacomponent) at a sampling location of a luma component. As shown in FIG.10, Equation (20) may be utilized to determine the chroma component(e.g., red difference chroma component and/or blue difference chromacomponent) at the luma component sampling locations L5, L7, L13 and L15.If the remainder of the division of the x coordinate by two is zero, andthe remainder of the division of the y coordinate by two is zero, thevideo coding device may utilize the interpolation filter in Equation(21) to determine the chroma component (e.g., red difference chromacomponent and/or blue difference chroma component) at a samplinglocation of a luma component. As shown in FIG. 10, Equation (21) may beutilized to determine the chroma component (e.g., red difference chromacomponent and/or blue difference chroma component) at the luma componentsampling locations L0, L2, L8 and L10. If the remainder of the divisionof the x coordinate by two is one, and the remainder of the division ofthe y coordinate by two is zero, the video coding device may utilize theinterpolation filter in Equation (22) to determine the chroma component(e.g., red difference chroma component and/or blue difference chromacomponent) at a sampling location of a luma component. As shown in FIG.10, Equation (22) may be utilized to determine the chroma component(e.g., red difference chroma component and/or blue difference chromacomponent) at the luma component sampling locations L1, L3, L9 and L11.

The chroma component at the sampling location L4 may be derived usingEquation (19):C(L4)=(C0*3+C2+2)>>2  (19)where >>2 may mean the sum of (C0*3+C2+2) is divided by 2² and/or >>2 iscalculated using right shift by two. If the sum of (C0*3+C2+2) is not aninteger, the decimal may be disregarded prior to dividing the sum by 2².In Equation (19), to determine the chroma component at the samplinglocation L4, a video coding device may apply an interpolation filter inwhich the chroma component (e.g., C_(r) 0 or C_(b) 0) at samplinglocation C0 is multiplied by three, then the sum is added to the chromacomponent (e.g., C_(r) 2 or C_(b) 2) at a different chroma samplinglocation C2, and that sum is added to two to determine a final sum. Aninteger value of the final sum may be determined. The interpolationfiler may divide the integer sum by four to determine the chromacomponent at the sampling location L4. The value of a plurality ofchroma components (e.g., c_(r) and c_(b), u and v, etc.) at the samplinglocation L4 may be determined using an interpolation filer (e.g.,Equation (19)). The chroma component at other sampling locations (e.g.,the sampling locations L6, L14, L112) may be determined using Equation(19) using the chroma component at the appropriate sampling locations.

The chroma component at the sampling location L8 may be derived usingEquation (20). The chroma component at the sampling location L8 may besimilar to the derived chroma component for the sampling location L4.Equation (20) is provided herein:C(L8)=(C0+C2*3+2)>>2  (20)where >>2 may mean the sum of (C0+C2*3+2) is divided by 2² and/or >>2 iscalculated using right shift by two. If the sum of (C0+C2*3+2) is not aninteger, the decimal may be disregarded prior to dividing the sum by 2².In Equation (20), to determine the chroma component at the samplinglocation L8, a video coding device may apply an interpolation filter inwhich the chroma component (e.g., C_(r) 2 or C_(b) 2) at samplinglocation C2 is multiplied by three, then the sum is added to the chromacomponent (e.g., C_(r) 0 or C_(b) 0) at a different sampling locationC0, and that sum is added to two to determine a final sum. An integervalue of the final sum may be determined. The interpolation filer maydivide the integer sum by four to determine the chroma component at thesampling location L8. The chroma component for sampling locations L8,L2, L10 may be determined using Equation (20) with the appropriatesampling locations of the chroma component. The value of a plurality ofchroma components (e.g., C_(r) and C_(b), u and v, etc.) at the samplinglocation L8 may be determined using an interpolation filer (e.g.,Equation (20)).

The chroma component at the sampling location L5 may be determined usingEquation (21), for example, as follows:C(L5)=((C0+C1)*3+(C2+C3)+4)>>3  (21)where >>3 may mean the sum of ((C0+C1)*3+(C2+C3)+4) is divided by 2³and/or >>3 is calculated using right shift by three. If the sum of((C0+C1)*3+(C2+C3)+4) is not an integer, the decimal may be disregardedprior to dividing the sum by 2³. In Equation (21), to determine thechroma component at the sampling location L5, a video coding device mayapply an interpolation filter in which the chroma component (e.g., C_(r)0 or C_(b) 0) at sampling location C0 is added to the chroma component(e.g., C_(r) 1 and C_(b) 1) at a different sampling location C1. Thevideo coding device may then multiply the sum of the sampling locationC1 and the sampling location C0 by three, and add the multiplied sum tothe chroma component at the sampling location C2 (e.g., C_(r) 2 andC_(b) 2), the chroma component at the sampling location C3 (e.g., C_(r)3 and C_(b) 3) and four to determine a final sum. An integer value ofthe final sum may be determined. The video coding device may then dividethis integer value by eight to determine the chroma component at thesampling location L5. The chroma component for sampling locations L7,L13, L15 may be determined using Equation (21) with the appropriatesampling locations of the chroma component. The value of a plurality ofchroma components (e.g., C_(r) and C_(b), u and v, etc.) at the samplinglocations L5 may be determined using an interpolation filter (e.g.,Equation (21)).

The derived chroma component for luma component at sampling location L9may be similar to the derived chroma component for the luma component atsampling location L5. The chroma component at the sampling location L9may be determined using Equation (22), for example, as follows:C(L9)=((C0+C1)+(C2+C5)*3+4)>>3  (22)where >>3 may mean the sum of ((C0+C1)+(C2+C5)*3+4) is divided by 2³and/or >>3 is calculated using right shift by three. If the sum of((C0+C1)+(C2+C5)*3+4) is not an integer, the decimal may be disregardedprior to dividing the sum by 2³. In Equation (22), to determine thechroma component at the sampling location L9, a video coding device mayapply an interpolation filter in which the chroma component C0 (e.g.,C_(r) 0 or C_(b) 0) at sampling location C0 is added to the chromacomponent C1 (e.g., C_(r) 1 or C_(b) 1) at sampling location C1. Thevideo coding device may then add the chroma component (e.g., C_(r) 2 orC_(b) 2) at sampling location C2 to the chroma component (e.g., C_(r) 5or C_(b) 5) at a different sampling location C5. The video coding devicemay then multiply the sum of the chroma component at the samplinglocation C2 and the chroma component at the sampling location C5 bythree, and the multiplied sum may be added to the sum the chromacomponent at the sampling location C0 and the chroma component at thesampling location C1 and four to determine a final sum. An integer valueof the final sum may be determined. The video coding device may thendivide this integer value by eight to determine the chroma component atthe sampling location L9. The chroma component for sampling locationsL11, L1, L3 may be determined using Equation (22) with the appropriatechroma component sampling locations.

The interpolation filter for the luma component at the samplinglocations L4 and L8 may be a two-tap filter, for example, a two-tapfilter [1, 3] and [3, 1], respectively. For example, the interpolationfiler for the luma component at the sampling location L4 and L8 may bethe interpolation filter described with reference to Equation (19) andEquation (20), respectively. The interpolation filter for the lumacomponent at the sampling locations L5 and L9 may be a four-tap filter,for example, a four-tap filter [3, 3, 1, 1] and [1, 1, 3, 3],respectively. For example, the interpolation filer for the lumacomponent at the sampling location L5 and L9 may be the interpolationfilter described with reference to Equation (21) and Equation (22),respectively.

The video coding device may be configured to apply a first interpolationfilter to a chroma component at a first sampling location and the secondinterpolation to a chroma component at a second sampling location, etc.For example, the video coding device may be configured to apply one ormore of Equations (17)-(18) to one or more of two overlapping chromacomponents (e.g., a red difference chroma component and/or a bluedifference chroma component) at one or more sampling locations. Forexample, the video coding device may apply Equation (17) to the chromacomponent at a first sampling location then apply Equation (18) to thechroma component at a second sampling location, and then apply Equation(17) to the chroma component at a third sampling location, etc.Similarly, the video coding device may be configured to apply a firstinterpolation filter to a luma component at a first sampling locationand a second interpolation to the luma component at a second samplinglocation, etc. For example, the video coding device may be configured toapply one or more of Equations (19)-(22) to a luma component at one ormore sampling locations. For example, the video coding device may applyEquation (19) to the luma component at a first sampling location,Equation (20) to the luma component at a second sampling location,Equation (21) to the luma component at a third sampling location,Equation (22) to the luma component at a fourth sampling location, etc.

FIG. 11A depicts a diagram of an example communications system 1100 inwhich one or more disclosed embodiments may be implemented and/or may beused. The communications system 1100 may be a multiple access systemthat provides content, such as voice, data, video, messaging, broadcast,etc., to multiple wireless users. The communications system 1100 mayenable multiple wireless users to access such content through thesharing of system resources, including wireless bandwidth. For example,the communications systems 1100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

As shown in FIG. 11A, the communications system 1100 may includewireless transmit/receive units (WTRUs) 1102 a, 1102 b, 1102 c, and/or1102 d (which generally or collectively may be referred to as WTRU1102), a radio access network (RAN) 1103/1104/1105, a core network1106/1107/1109, a public switched telephone network (PSTN) 1108, theInternet 1110, and other networks 1112, though it will be appreciatedthat the disclosed embodiments contemplate any number of WTRUs, basestations, networks, and/or network elements. Each of the WTRUs 1102 a,1102 b, 1102 c, and/or 1102 d may be any type of device configured tooperate and/or communicate in a wireless environment. By way of example,the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d may be configured totransmit and/or receive wireless signals and may include user equipment(UE), a mobile station, a fixed or mobile subscriber unit, a pager, acellular telephone, a personal digital assistant (PDA), a smartphone, alaptop, a netbook, a personal computer, a wireless sensor, consumerelectronics, and the like.

The communications systems 1100 may also include a base station 1114 aand a base station 1114 b. Each of the base stations 1114 a, 1114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d to facilitateaccess to one or more communication networks, such as the core network1106/1107/1109, the Internet 1110, and/or the networks 1112. By way ofexample, the base stations 1114 a and/or 1114 b may be a basetransceiver station (BTS), a Node-B, an eNode B, a Home Node B, a HomeeNode B, a site controller, an access point (AP), a wireless router, andthe like. While the base stations 1114 a, 1114 b are each depicted as asingle element, it will be appreciated that the base stations 1114 a,1114 b may include any number of interconnected base stations and/ornetwork elements.

The base station 1114 a may be part of the RAN 1103/1104/1105, which mayalso include other base stations and/or network elements (not shown),such as a base station controller (BSC), a radio network controller(RNC), relay nodes, etc. The base station 1114 a and/or the base station1114 b may be configured to transmit and/or receive wireless signalswithin a particular geographic region, which may be referred to as acell (not shown). The cell may further be divided into cell sectors. Forexample, the cell associated with the base station 1114 a may be dividedinto three sectors. Thus, in one embodiment, the base station 1114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 1114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 1114 a and/or 1114 b may communicate with one or moreof the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d over an air interface1115/1116/1117, which may be any suitable wireless communication link(e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV),visible light, etc.). The air interface 1115/1116/1117 may beestablished using any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 1100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 1114 a in the RAN 1103/1104/1105 and the WTRUs1102 a, 1102 b, and/or 1102 c may implement a radio technology such asUniversal Mobile Telecommunications System (UMTS) Terrestrial RadioAccess (UTRA), which may establish the air interface 1115/1116/1117using wideband CDMA (WCDMA). WCDMA may include communication protocolssuch as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+).HSPA may include High-Speed Downlink Packet Access (HSDPA) and/orHigh-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 1114 a and the WTRUs 1102 a,1102 b, and/or 1102 c may implement a radio technology such as EvolvedUMTS Terrestrial Radio Access (E-UTRA), which may establish the airinterface 1115/1116/1117 using Long Term Evolution (LTE) and/orLTE-Advanced (LTE-A).

In other embodiments, the base station 1114 a and the WTRUs 1102 a, 1102b, and/or 1102 c may implement radio technologies such as IEEE 802.16(i.e., Worldwide Interoperability for Microwave Access (WiMAX)),CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000),Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), GlobalSystem for Mobile communications (GSM), Enhanced Data rates for GSMEvolution (EDGE), GSM EDGE (GERAN), and the like.

The base station 1114 b in FIG. 11A may be a wireless router, Home NodeB, Home eNode B, or access point, for example, and may utilize anysuitable RAT for facilitating wireless connectivity in a localized area,such as a place of business, a home, a vehicle, a campus, and the like.In one embodiment, the base station 1114 b and the WTRUs 1102 c, 1102 dmay implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In another embodiment, the basestation 1114 b and the WTRUs 1102 c, 1102 d may implement a radiotechnology such as IEEE 802.15 to establish a wireless personal areanetwork (WPAN). In yet another embodiment, the base station 114 b andthe WTRUs 102 c, 1102 d may utilize a cellular-based RAT (e.g., WCDMA,CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell.As shown in FIG. 11A, the base station 1114 b may have a directconnection to the Internet 1110. Thus, the base station 1114 b may notbe required to access the Internet 1110 via the core network1106/1107/1109.

The RAN 1103/1104/1105 may be in communication with the core network1106/1107/1109, which may be any type of network configured to providevoice, data, applications, and/or voice over internet protocol (VoIP)services to one or more of the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102d. For example, the core network 1106/1107/1109 may provide callcontrol, billing services, mobile location-based services, pre-paidcalling, Internet connectivity, video distribution, etc., and/or performhigh-level security functions, such as user authentication. Although notshown in FIG. 11A, it will be appreciated that the RAN 1103/1104/1105and/or the core network 1106/1107/1109 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN1103/1104/1105 or a different RAT. For example, in addition to beingconnected to the RAN 1103/1104/1105, which may be utilizing an E-UTRAradio technology, the core network 1106/1107/1109 may also be incommunication with another RAN (not shown) employing a GSM radiotechnology.

The core network 1106/1107/1109 may also serve as a gateway for theWTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d to access the PSTN 1108, theInternet 1110, and/or other networks 112. The PSTN 1108 may includecircuit-switched telephone networks that provide plain old telephoneservice (POTS). The Internet 1110 may include a global system ofinterconnected computer networks and devices that use commoncommunication protocols, such as the transmission control protocol(TCP), user datagram protocol (UDP) and the internet protocol (IP) inthe TCP/IP internet protocol suite. The networks 1112 may include wiredor wireless communications networks owned and/or operated by otherservice providers. For example, the networks 1112 may include anothercore network connected to one or more RANs, which may employ the sameRAT as the RAN 1103/1104/1105 or a different RAT.

Some or all of the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d in thecommunications system 1100 may include multi-mode capabilities, i.e.,the WTRUs 1102 a, 1102 b, 1102 c, and/or 1102 d may include multipletransceivers for communicating with different wireless networks overdifferent wireless links. For example, the WTRU 1102 c shown in FIG. 11Amay be configured to communicate with the base station 1114 a, which mayemploy a cellular-based radio technology, and with the base station 1114b, which may employ an IEEE 802 radio technology.

FIG. 11B depicts a system diagram of an example WTRU 1102. As shown inFIG. 11B, the WTRU 1102 may include a processor 1118, a transceiver1120, a transmit/receive element 1122, a speaker/microphone 1124, akeypad 1126, a display/touchpad 1128, non-removable memory 1130,removable memory 1132, a power source 1134, a global positioning system(GPS) chipset 1136, and other peripherals 1138. It will be appreciatedthat the WTRU 1102 may include any sub-combination of the foregoingelements while remaining consistent with an embodiment. Also,embodiments contemplate that the base stations 1114 a and 1114 b, and/orthe nodes that base stations 1114 a and 1114 b may represent, such asbut not limited to transceiver station (BTS), a Node-B, a sitecontroller, an access point (AP), a home node-B, an evolved home node-B(eNodeB), a home evolved node-B (HeNB), a home evolved node-B gateway,and proxy nodes, among others, may include some or all of the elementsdepicted in FIG. 11B and described herein.

The processor 1118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 1118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 1102 to operate in a wirelessenvironment. The processor 1118 may be coupled to the transceiver 1120,which may be coupled to the transmit/receive element 1122. While FIG.11B depicts the processor 1118 and the transceiver 1120 as separatecomponents, it may be appreciated that the processor 1118 and thetransceiver 1120 may be integrated together in an electronic package orchip.

The transmit/receive element 1122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 1114a) over the air interface 1115/1116/1117. For example, in oneembodiment, the transmit/receive element 1122 may be an antennaconfigured to transmit and/or receive RF signals. In another embodiment,the transmit/receive element 1122 may be an emitter/detector configuredto transmit and/or receive IR, UV, or visible light signals, forexample. In yet another embodiment, the transmit/receive element 1122may be configured to transmit and receive both RF and light signals. Itwill be appreciated that the transmit/receive element 1122 may beconfigured to transmit and/or receive any combination of wirelesssignals.

In addition, although the transmit/receive element 1122 is depicted inFIG. 11B as a single element, the WTRU 1102 may include any number oftransmit/receive elements 1122. More specifically, the WTRU 1102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 1102 mayinclude two or more transmit/receive elements 1122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 1115/1116/1117.

The transceiver 1120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 1122 and to demodulatethe signals that are received by the transmit/receive element 1122. Asnoted above, the WTRU 1102 may have multi-mode capabilities. Thus, thetransceiver 1120 may include multiple transceivers for enabling the WTRU1102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 1118 of the WTRU 1102 may be coupled to, and may receiveuser input data from, the speaker/microphone 1124, the keypad 1126,and/or the display/touchpad 1128 (e.g., a liquid crystal display (LCD)display unit or organic light-emitting diode (OLED) display unit). Theprocessor 1118 may also output user data to the speaker/microphone 1124,the keypad 1126, and/or the display/touchpad 1128. In addition, theprocessor 1118 may access information from, and store data in, any typeof suitable memory, such as the non-removable memory 1130 and/or theremovable memory 1132. The non-removable memory 1130 may includerandom-access memory (RAM), read-only memory (ROM), a hard disk, or anyother type of memory storage device. The removable memory 1132 mayinclude a subscriber identity module (SIM) card, a memory stick, asecure digital (SD) memory card, and the like. In other embodiments, theprocessor 1118 may access information from, and store data in, memorythat is not physically located on the WTRU 1102, such as on a server ora home computer (not shown).

The processor 1118 may receive power from the power source 1134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 1102. The power source 1134 may be any suitabledevice for powering the WTRU 1102. For example, the power source 1134may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 1118 may also be coupled to the GPS chipset 1136, whichmay be configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 1102. In additionto, or in lieu of, the information from the GPS chipset 1136, the WTRU1102 may receive location information over the air interface1115/1116/1117 from a base station (e.g., base stations 1114 a, 1114 b)and/or determine its location based on the timing of the signals beingreceived from two or more nearby base stations. It will be appreciatedthat the WTRU 1102 may acquire location information by way of anysuitable location-determination method while remaining consistent withan embodiment.

The processor 1118 may further be coupled to other peripherals 1138,which may include one or more software and/or hardware modules thatprovide additional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 1138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 11C depicts a system diagram of the RAN 1103 and the core network1106 according to an embodiment. As noted above, the RAN 1103 may employa UTRA radio technology to communicate with the WTRUs 1102 a, 1102 b,and/or 1102 c over the air interface 1115. The RAN 1103 may also be incommunication with the core network 1106. As shown in FIG. 11C, the RAN1103 may include Node-Bs 1140 a, 1140 b, and/or 1140 c, which may eachinclude one or more transceivers for communicating with the WTRUs 1102a, 1102 b, and/or 1102 c over the air interface 1115. The Node-Bs 1140a, 1140 b, and/or 1140 c may each be associated with a particular cell(not shown) within the RAN 1103. The RAN 1103 may also include RNCs 1142a and/or 1142 b. It will be appreciated that the RAN 1103 may includeany number of Node-Bs and RNCs while remaining consistent with anembodiment.

As shown in FIG. 11C, the Node-Bs 1140 a and/or 1140 b may be incommunication with the RNC 1142 a. Additionally, the Node-B 1140 c maybe in communication with the RNC 1142 b. The Node-Bs 1140 a, 1140 b,and/or 1140 c may communicate with the respective RNCs 1142 a, 1142 bvia an Iub interface. The RNCs 1142 a, 1142 b may be in communicationwith one another via an Iur interface. Each of the RNCs 1142 a, 1142 bmay be configured to control the respective Node-Bs 1140 a, 1140 b,and/or 1140 c to which it is connected. In addition, each of the RNCs1142 a, 1142 b may be configured to carry out or support otherfunctionality, such as outer loop power control, load control, admissioncontrol, packet scheduling, handover control, macrodiversity, securityfunctions, data encryption, and the like.

The core network 1106 shown in FIG. 11C may include a media gateway(MGW) 1144, a mobile switching center (MSC) 1146, a serving GPRS supportnode (SGSN) 1148, and/or a gateway GPRS support node (GGSN) 1150. Whileeach of the foregoing elements are depicted as part of the core network1106, it will be appreciated that any one of these elements may be ownedand/or operated by an entity other than the core network operator.

The RNC 1142 a in the RAN 1103 may be connected to the MSC 1146 in thecore network 1106 via an IuCS interface. The MSC 1146 may be connectedto the MGW 1144. The MSC 1146 and the MGW 1144 may provide the WTRUs1102 a, 1102 b, and/or 1102 c with access to circuit-switched networks,such as the PSTN 1108, to facilitate communications between the WTRUs1102 a, 1102 b, and/or 1102 c and traditional land-line communicationsdevices.

The RNC 1142 a in the RAN 1103 may also be connected to the SGSN 1148 inthe core network 1106 via an IuPS interface. The SGSN 1148 may beconnected to the GGSN 1150. The SGSN 1148 and the GGSN 1150 may providethe WTRUs 1102 a, 1102 b, and/or 1102 c with access to packet-switchednetworks, such as the Internet 1110, to facilitate communicationsbetween and the WTRUs 1102 a, 1102 b, and/or 1102 c and IP-enableddevices.

As noted above, the core network 1106 may also be connected to thenetworks 1112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

FIG. 11D depicts a system diagram of the RAN 1104 and the core network1107 according to an embodiment. As noted above, the RAN 1104 may employan E-UTRA radio technology to communicate with the WTRUs 1102 a, 1102 b,and/or 1102 c over the air interface 1116. The RAN 1104 may also be incommunication with the core network 1107.

The RAN 1104 may include eNode-Bs 1160 a, 1160 b, and/or 1160 c, thoughit will be appreciated that the RAN 1104 may include any number ofeNode-Bs while remaining consistent with an embodiment. The eNode-Bs1160 a, 1160 b, and/or 1160 c may each include one or more transceiversfor communicating with the WTRUs 1102 a, 1102 b, and/or 1102 c over theair interface 1116. In one embodiment, the eNode-Bs 1160 a, 1160 b,and/or 1160 c may implement MIMO technology. Thus, the eNode-B 1160 a,for example, may use multiple antennas to transmit wireless signals to,and receive wireless signals from, the WTRU 1102 a.

Each of the eNode-Bs 1160 a, 1160 b, and/or 1160 c may be associatedwith a particular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 11D, theeNode-Bs 1160 a, 1160 b, and/or 1160 c may communicate with one anotherover an X2 interface.

The core network 1107 shown in FIG. 11D may include a mobilitymanagement gateway (MME) 1162, a serving gateway 1164, and a packet datanetwork (PDN) gateway 1166. While each of the foregoing elements aredepicted as part of the core network 1107, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 1162 may be connected to each of the eNode-Bs 1160 a, 1160 b,and/or 1160 c in the RAN 1104 via an S1 interface and may serve as acontrol node. For example, the MME 1162 may be responsible forauthenticating users of the WTRUs 1102 a, 1102 b, and/or 1102 c, beareractivation/deactivation, selecting a particular serving gateway duringan initial attach of the WTRUs 1102 a, 1102 b, and/or 1102 c, and thelike. The MME 1162 may also provide a control plane function forswitching between the RAN 104 and other RANs (not shown) that employother radio technologies, such as GSM or WCDMA.

The serving gateway 1164 may be connected to each of the eNode-Bs 1160a, 1160 b, and/or 1160 c in the RAN 1104 via the S1 interface. Theserving gateway 1164 may generally route and forward user data packetsto/from the WTRUs 1102 a, 1102 b, and/or 1102 c. The serving gateway1164 may also perform other functions, such as anchoring user planesduring inter-eNode B handovers, triggering paging when downlink data isavailable for the WTRUs 1102 a, 1102 b, and/or 1102 c, managing andstoring contexts of the WTRUs 1102 a, 1102 b, and/or 1102 c, and thelike.

The serving gateway 1164 may also be connected to the PDN gateway 1166,which may provide the WTRUs 1102 a, 1102 b, and/or 1102 c with access topacket-switched networks, such as the Internet 1110, to facilitatecommunications between the WTRUs 1102 a, 1102 b, and/or 1102 c andIP-enabled devices.

The core network 1107 may facilitate communications with other networks.For example, the core network 1107 may provide the WTRUs 1102 a, 1102 b,and/or 1102 c with access to circuit-switched networks, such as the PSTN1108, to facilitate communications between the WTRUs 1102 a, 1102 b,and/or 1102 c and traditional land-line communications devices. Forexample, the core network 1107 may include, or may communicate with, anIP gateway (e.g., an IP multimedia subsystem (IMS) server) that servesas an interface between the core network 1107 and the PSTN 1108. Inaddition, the core network 1107 may provide the WTRUs 1102 a, 1102 b,and/or 1102 c with access to the networks 1112, which may include otherwired or wireless networks that are owned and/or operated by otherservice providers.

FIG. 11E depicts a system diagram of the RAN 1105 and the core network1109 according to an embodiment. The RAN 1105 may be an access servicenetwork (ASN) that employs IEEE 802.16 radio technology to communicatewith the WTRUs 1102 a, 1102 b, and/or 1102 c over the air interface1117. As will be further discussed below, the communication linksbetween the different functional entities of the WTRUs 1102 a, 1102 b,and/or 1102 c, the RAN 1105, and the core network 1109 may be defined asreference points.

As shown in FIG. 11E, the RAN 1105 may include base stations 1180 a,1180 b, and/or 1180 c, and an ASN gateway 1182, though it will beappreciated that the RAN 1105 may include any number of base stationsand ASN gateways while remaining consistent with an embodiment. The basestations 1180 a, 1180 b, and/or 1180 c may each be associated with aparticular cell (not shown) in the RAN 1105 and may each include one ormore transceivers for communicating with the WTRUs 1102 a, 1102 b,and/or 1102 c over the air interface 1117. In one embodiment, the basestations 1180 a, 1180 b, and/or 1180 c may implement MIMO technology.Thus, the base station 1180 a, for example, may use multiple antennas totransmit wireless signals to, and receive wireless signals from, theWTRU 1102 a. The base stations 1180 a, 1180 b, and/or 1180 c may alsoprovide mobility management functions, such as handoff triggering,tunnel establishment, radio resource management, traffic classification,quality of service (QoS) policy enforcement, and the like. The ASNgateway 1182 may serve as a traffic aggregation point and may beresponsible for paging, caching of subscriber profiles, routing to thecore network 1109, and the like.

The air interface 1117 between the WTRUs 1102 a, 1102 b, and/or 1102 cand the RAN 1105 may be defined as an R1 reference point that implementsthe IEEE 802.16 specification. In addition, each of the WTRUs 1102 a,1102 b, and/or 1102 c may establish a logical interface (not shown) withthe core network 1109. The logical interface between the WTRUs 1102 a,1102 b, and/or 1102 c and the core network 1109 may be defined as an R2reference point, which may be used for authentication, authorization, IPhost configuration management, and/or mobility management.

The communication link between each of the base stations 1180 a, 1180 b,and/or 1180 c may be defined as an R8 reference point that includesprotocols for facilitating WTRU handovers and the transfer of databetween base stations. The communication link between the base stations1180 a, 1180 b, and/or 1180 c and the ASN gateway 1182 may be defined asan R6 reference point. The R6 reference point may include protocols forfacilitating mobility management based on mobility events associatedwith each of the WTRUs 1102 a, 1102 b, and/or 1102 c.

As shown in FIG. 11E, the RAN 1105 may be connected to the core network1109. The communication link between the RAN 1105 and the core network1109 may defined as an R3 reference point that includes protocols forfacilitating data transfer and mobility management capabilities, forexample. The core network 1109 may include a mobile IP home agent(MIP-HA) 1184, an authentication, authorization, accounting (AAA) server1186, and a gateway 1188. While each of the foregoing elements aredepicted as part of the core network 1109, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MIP-HA may be responsible for IP address management, and may enablethe WTRUs 1102 a, 1102 b, and/or 1102 c to roam between different ASNsand/or different core networks. The MIP-HA 1184 may provide the WTRUs1102 a, 1102 b, and/or 1102 c with access to packet-switched networks,such as the Internet 1110, to facilitate communications between theWTRUs 1102 a, 1102 b, and/or 1102 c and IP-enabled devices. The AAAserver 1186 may be responsible for user authentication and forsupporting user services. The gateway 1188 may facilitate interworkingwith other networks. For example, the gateway 1188 may provide the WTRUs1102 a, 1102 b, and/or 1102 c with access to circuit-switched networks,such as the PSTN 1108, to facilitate communications between the WTRUs1102 a, 1102 b, and/or 1102 c and traditional land-line communicationsdevices. In addition, the gateway 1188 may provide the WTRUs 1102 a,1102 b, and/or 1102 c with access to the networks 1112, which mayinclude other wired or wireless networks that are owned and/or operatedby other service providers.

Although not shown in FIG. 11E, it should, may, and/or will beappreciated that the RAN 1105 may be connected to other ASNs and thecore network 1109 may be connected to other core networks. Thecommunication link between the RAN 1105 the other ASNs may be defined asan R4 reference point, which may include protocols for coordinating themobility of the WTRUs 1102 a, 1102 b, and/or 1102 c between the RAN 1105and the other ASNs. The communication link between the core network 1109and the other core networks may be defined as an R5 reference, which mayinclude protocols for facilitating interworking between home corenetworks and visited core networks.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed:
 1. A video coding device, comprising: a processorconfigured to: receive a picture associated with a first color spacethat covers a first volume of colors, wherein the picture ischaracterized by a chroma format where luma sampling locations andchroma sampling locations are misaligned, and the picture comprises afirst component at a first sampling location, a second component at asecond sampling location and the second component at a third samplinglocation, apply a first interpolation filter to the second component atthe second sampling location and the second component at the thirdsampling location to determine the second component at the firstsampling location, wherein the second component at the first samplinglocation is associated with the first color space, wherein when thefirst component is a luma component, the first sampling location is aluma sampling location and the first interpolation filter is applied toa chroma component at the second and the third sampling locations todetermine the chroma component at the luma sampling location, and whenthe first component is the chroma component, the first sampling locationis a chroma sampling location, and the first interpolation filter isapplied to the luma component at the second and the third samplinglocations to determine the luma component at the chroma samplinglocation; and apply a color conversion model to the first component atthe first sampling location and to the second component at the firstsampling location to translate the first component at the first samplinglocation from the first color space to a second color space that coversa broader volume of colors compared to the first volume of colors. 2.The video coding device of claim 1, wherein the first component is aluma component and the second component is a first chroma component or asecond chroma component, or wherein the first component is the firstchroma component or the second chroma component and the second componentis the luma component.
 3. The video coding device of claim 2, whereinthe processor is further configured to: add the second component at thesecond sampling location, the second component at the third samplinglocation, and one to determine a sum; and divide the sum by two.
 4. Thevideo coding device of claim 1, wherein the processor is furtherconfigured to: multiply the second component at the second samplinglocation by three; add the multiplied second component at the secondsampling location, the second component at the third sampling location,and two to determine a sum; and divide the sum by four.
 5. The videocoding device of claim 1, wherein the picture comprises the secondcomponent at a fourth sampling location and the second component at afifth sampling location; and wherein the processor is configured toapply the first interpolation filter to the second component at thesecond sampling location, the second component at the third samplinglocation, the second component at the fourth sampling location, and thesecond component at the fifth sampling location to determine the secondcomponent at the first sampling location.
 6. The video coding device ofclaim 5, wherein the processor is further configured to: add the secondcomponent at the second sampling location and the second component atthe third sampling location to determine a first sum; add the secondcomponent at the fourth sampling location and the second component atthe fifth sampling location to determine a second sum; multiply thesecond sum by three to determine a third sum; add the first sum, thethird sum, and four to determine a fourth sum; and divide the fourth sumby eight.
 7. The video coding device of claim 1, wherein the picturecomprises a third component at the second sampling location and thethird component at the third sampling location, wherein the firstcomponent is a luma component, the second component is a first chromacomponent, and the third component is a second chroma component, andwherein the processor is further configured to: apply the firstinterpolation filter to the third component at the second samplinglocation and the third component at the third sampling location todetermine the third component at the first sampling location, whereinthe third component at the first sampling location is associated withthe first color space; and apply the color conversion model to the firstcomponent at the first sampling location, to the second component at thefirst sampling location, and to the third component at the firstsampling location to translate the first component at the first samplinglocation to the second color space.
 8. The video coding device of claim1, wherein the picture comprises a third component at the first samplinglocation, and wherein the processor is further configured to: apply thecolor conversion model to the first component at the first samplinglocation, to the third component at the first sampling location and tothe second component at the first sampling location to translate thefirst component at the first sampling location to the second colorspace.
 9. The video coding device of claim 8, wherein the firstcomponent is a first chroma component, the second component is a lumacomponent, and the third component is a second chroma component, orwherein the first component is the second chroma component, the secondcomponent is the luma component, and the third component is the firstchroma component.
 10. The video coding device of claim 1, wherein thepicture is characterized by at least one of: a 4:2:0 chroma format or a4:2:2 chroma format.
 11. The video coding device of claim 1, wherein thecolor conversion model is based on a 3-dimensional look up table (LUT).12. The video coding device of claim 1, wherein the processor is furtherconfigured to receive a scalable bitstream, the scalable bitstreamcomprising a base layer and an enhancement layer, wherein the base layercomprises the picture, the base layer is associated with the first colorspace and the enhancement layer is associated with the second colorspace, and the color-converted first and second components are used forinter-layer prediction.
 13. A video coding device, comprising: aprocessor configured to: receive a picture associated with a first colorspace that covers a first volume of colors, wherein the picture ischaracterized by a chroma format where luma sampling locations andchroma sampling locations are misaligned, and the picture comprises aluma component at a first sampling location, a first chroma component ata second sampling location, a second chroma component at the secondsampling location, the first chroma component at a third samplinglocation, the second chroma component at the third sampling location,the first chroma component at a fourth sampling location, the secondchroma component at the fourth sampling location, the first chromacomponent at a fifth sampling location, and the second chroma componentat the fifth sampling location; apply an interpolation filter to two ormore of the first chroma component at the second sampling location, thefirst chroma component at the third sampling location, the first chromacomponent at the fourth sampling location, and the first chromacomponent at the fifth sampling location to determine the first chromacomponent at the first sampling location of the luma component, whereinthe first chroma component at the first sampling location is associatedwith the first color space; apply the interpolation filter to two ormore of the second chroma component at the second sampling location, thesecond chroma component at the third sampling location, the secondchroma component at the fourth sampling location, and the second chromacomponent at the fifth sampling location to determine the second chromacomponent at the first sampling location of the luma component, whereinthe second chroma component at the first sampling location is associatedwith the first color space; and apply a color conversion model to theluma component at the first sampling location, the first chromacomponent at the first sampling location, and the second chromacomponent at the first sampling location to translate the luma componentat the first sampling location from the first color space to a secondcolor space that covers a broader volume of colors compared to the firstvolume of colors.
 14. A video coding device, comprising: a processorconfigured to: receive a picture associated with a first color spacethat covers a first volume of colors, wherein the picture ischaracterized by a chroma format where luma sampling locations andchroma sampling locations are misaligned, and the picture comprises afirst chroma component at a first sampling location, a second chromacomponent at the first sampling location, a luma component at a secondsampling location, the luma component at a third sampling location, theluma component at a fourth sampling location, and the luma component ata fifth sampling location; apply an interpolation filter to two or moreof the luma component at the second sampling location, the lumacomponent at the third sampling location, the luma component at thefourth sampling location, and the luma component at the fifth samplinglocation to determine the luma component at the first sampling locationof the first chroma component, wherein the luma component at the firstsampling location is associated with the first color space; apply acolor conversion model to the first chroma component at the firstsampling location, the second chroma component at the first samplinglocation, and to the luma component at the first sampling location totranslate the first chroma component at the first sampling location fromthe first color space to a second color space that covers a broadervolume of colors compared to the first volume of colors; and apply thecolor conversion model to the first chroma component at the firstsampling location, the second chroma component at the first samplinglocation, and to the luma component at the first sampling location totranslate the second chroma component at the first sampling location tothe second color space.
 15. A video coding method, comprising: receivinga picture associated with a first color space that covers a first volumeof colors, wherein the picture is characterized by a chroma format whereluma sampling locations and chroma sampling locations are misaligned,and the picture comprises a first component at a first samplinglocation, a second component at a second sampling location and thesecond component at a third sampling location, applying a firstinterpolation filter to the second component at the second samplinglocation and the second component at the third sampling location todetermine the second component at the first sampling location, whereinthe second component at the first sampling location is associated withthe first color space, wherein when the first component is a lumacomponent, the first sampling location is a luma sampling location andthe first interpolation filter is applied to a chroma component at thesecond and the third sampling locations to determine the chromacomponent at the luma sampling location, and when the first component isthe chroma component, the first sampling location is a chroma samplinglocation, and the first interpolation filter is applied to the lumacomponent at the second and the third sampling locations to determinethe luma component at the chroma sampling location; and applying a colorconversion model to the first component at the first sampling locationand to the second component at the first sampling location to translatethe first component at the first sampling location from the first colorspace to a second color space that covers a broader volume of colorscompared to the first volume of colors.
 16. The video coding method ofclaim 15, wherein the first component is a luma component and the secondcomponent is a first chroma component or a second chroma component, orwherein the first component is the first chroma component or the secondchroma component and the second component is the luma component.
 17. Thevideo coding method of claim 16, wherein the method to apply the firstinterpolation filter further comprises: adding the second component atthe second sampling location, the second component at the third samplinglocation, and one to determine a sum; and dividing the sum by two. 18.The video coding method of claim 15, wherein the method to apply thefirst interpolation filter further comprises: multiplying the secondcomponent at the second sampling location by three; adding themultiplied second component at the second sampling location, the secondcomponent at the third sampling location, and two to determine a sum;and dividing the sum by four.
 19. The video coding method of claim 15,wherein the picture comprises the second component at a fourth samplinglocation and the second component at a fifth sampling location, andwherein the method further comprises: applying the first interpolationfilter to the second component at the second sampling location, thesecond component at the third sampling location, the second component atthe fourth sampling location, and the second component at the fifthsampling location to determine the second component at the firstsampling location.
 20. The video coding method of claim 19, wherein themethod to apply the first interpolation filter further comprises: addingthe second component at the second sampling location and the secondcomponent at the third sampling location to determine a first sum;adding the second component at the fourth sampling location and thesecond component at the fifth sampling location to determine a secondsum; multiplying the second sum by three to determine a third sum;adding the first sum, the third sum, and four to determine a fourth sum;and dividing the fourth sum by eight.
 21. The video coding method ofclaim 15, wherein the picture comprises a third component at the secondsampling location and the third component at the third samplinglocation, wherein the first component is a luma component, the secondcomponent is a first chroma component, and the third component is asecond chroma component, and wherein the method further comprises:applying the first interpolation filter to the third component at thesecond sampling location and the third component at the third samplinglocation to determine the third component at the first samplinglocation, wherein the third component at the first sampling location isassociated with the first color space; and applying the color conversionmodel to the first component at the first sampling location, to thesecond component at the first sampling location, and to the thirdcomponent at the first sampling location to translate the firstcomponent at the first sampling location to the second color space. 22.The video coding method of claim 15, wherein the picture comprises athird component at the first sampling location, and wherein the methodfurther comprises: applying the color conversion model to the firstcomponent at the first sampling location, to the third component at thefirst sampling location and to the second component at the firstsampling location to translate the first component at the first samplinglocation to the second color space.
 23. The video coding method of claim22, wherein the first component is a first chroma component, the secondcomponent is a luma component, and the third component is a secondchroma component, or wherein the first component is the second chromacomponent, the second component is the luma component, and the thirdcomponent is the first chroma component.